We represent lead-time by L. This lead-time could be due to order processing, manufacturing flow time, transportation time or any other types of delays. Therefore, because of the existence of lead-time between placing order and receiving the products into stock, we need to forecast demand. In the past research especially in the case of single product supply chains, various forecasting methods such as moving average, exponential smoothing, minimum expected mean squares of error are utilized to predict the lead-time demand and then a measure for bullwhip effect is derived for each situation. In case of multi-product supply chains, Chaharsooghi and Sadeghi (2009) considered a supply chain with two products in which retailer used moving average forecasting method for lead-time demand prediction. Here in this paper, to provide a useful comparison between two major forecasting methods (i.e. moving average and exponential smoothing) we suppose that retailer uses exponential smoothing forecasting method to predict lead-time demand and after that, results will be compared with the previous research conducted by Chaharsooghi and Sadeghi (2009) in case of moving average method.